1. Field of the Invention
This invention relates to a new mechanism for mechanically filtering suspended matter from aquarium water, and in particular to a submerged filtering apparatus adapted to cause full circulation and full filtering of all the water in the tank.
2. Description of the Prior Art
Harmful and potentially harmful substances (fish excretion, uneaten food, etc.) may gradually accumulate in aquarium water, eventually poisoning the animals. Only effective filtration can keep this from happening. Generally speaking, "filtration" can be defined as the removal of unwanted substances from the water. A successful aquarist uses three types of filters: biological, mechanical and chemical.
Biological filtration is solely the work of bacteria attached to the surfaces of gravel or other bottom material in the aquarium. Bacteria reaches the filter bed by various means: the air, the animals themselves, the food fed to the animals, and even the hands of the aquarist. As the water ages, the numbers of bacteria increase until the gravel teems with them. Generally speaking, biological filtration, may be defined as the removal of unwanted substances, primarily ammonia, from the water by bacteria. "Mechanical" filtration is the removal of suspended particles from the water. This function is performed by the gravel in the aquarium and in some systems by a filtering vibrous material through which the water is directed. Without mechanical filtration the water would be turbid instead of clear. "Chemical" filtration is defined as the removal of dissolved organics by adsorption, air-stripping, or direct oxidation to simpler chemical substances. For adsorption, activated carbon is the most reliable means. A main object of the present invention is to provide a quite simple and yet extremely effective filtration system for performing all three types of filtration.
The amount of animals an aquarium can safely hold is its "carrying capacity". More captive marine animals die from the result of overcrowding than from any other combination of factors. The animal load that an aquarium tank of given dimensions can accommodate is dependent to a considerable extent on the effectiveness of its filtration system. Accordingly, another object of this invention is to provide an improved filtration system which will result in a larger carrying capacity for any given aquarium tank.
A quite good discussion of the subject "filtration" can be found in the book Marine Aquarium Keeping, by Stephen Spotte, Director of Aquariums, Aquarium Systems, Inc., Eastlake, Ohio, published in 1973 by John Wiley & Sons, New York.
Various types of prior art filtering apparatus are disclosed by the following U.S. Pat.: U.S. Pat. No. 2,636,473 granted Apr. 28, 1953 to Albert J. Schwartz and Samuel H. Barbour; U.S. Pat. No. 2,676,921, granted Apr. 27, 1954, to Mary L. M. Vansteenkiste; U.S. Pat. No. 2,871,820, granted Feb. 3, 1959, to Edward F. Hayden; U.S. Pat. No. 2,935,199, granted May 3, 1960 to Allan H. Willinger; U.S. Pat. No. 3,418,973, granted Dec. 31, 1968, to Schinichi Saito; U.S. Pat. No. 3,487,440, granted Dec. 30, 1969 to Robert Newsteder; U.S. Pat. No. 3,516,544, granted June 23, 1970 to Walter Sesholtz; U.S. Pat. No. 3,529,574, granted Sept. 22, 1970, to William F. Kelley and Robert J. De Fasselle; U.S. Pat. No. 3,738,491, granted June 12, 1973, to Denzel J. Dockery; U.S. Pat. No. 3,720,319, granted Mar. 13, 1973, to Eugene B. White; and U.S. Pat. No. 3,827,560, granted Aug. 6, 1974, to Michael S. J. Morton. In addition to disclosing specific filtering systems these patents discuss the aquarium water cleaning problem and define various other filtration systems known to the particular patentee. These patents should be thoroughly considered together with the instant specification for the purpose of putting the present invention in proper perspective.
Most of the above-identified patents disclose filtration systems which have become known as "undergravel" filtration systems. Generally speaking, these systems comprise a relatively shallow platform on which the aquarium gravel is placed. Small openings are provided in the platform so that water can flow downwardly through such openings into the space below the platform. One or more airpipes are provided for causing the water to circulate in the tank and downwardly through the gravel. The main purpose of this type of system is to promote water movement through the gravel, so that the gravel can perform the filtering function. A disadvantage of this type of system is that it does not promote complete circulation of the water. As a result, only a portion of the water is filtered, leaving dead spots in the aquarium where untreated waste material collects. Also, most of the patented systems do not include any way of collecting and removing the waste material which collects in the compartment below the platform. As a result, it becomes necessary for the aquarist to completely remove everything from the aquarium in order to clean out such collected matter. This means that the gravel bed must be disturbed and this in turn means that the bacteria growth needed for biological filtration must be disturbed also. Thus, after each such cleaning the aging process must be repeated in order to return the aquarium to a condition in which biological filtration will occur. An object of this invention is to provide an aquarium filtering apparatus which causes a substantially full circulation of the water in the tank, so that substantially all of the water is continuously moved through the gravel filter bed. A further object of the invention is to provide aquarium filtering apparatus which includes means for mechanically filtering the water which flows through the chamber below the gravel supporting platform. The removed materials are collected in a housing which is removable from the aquarium without it being necessary to disturb the gravel bed.